The rise of the global population and demands for carbon-neutral biofuels have accelerated the need to improve agricultural productivity. An emerging strategy is to control plant reproduction and architecture to better fit specific environments and to increase crop densities. Increasing crop densities may be achieved by producing plants that perform well in more competitive environments. Plant architecture, timing of reproduction, and plant responses to competition may be manipulated to produce plants adapted to growing in crowded conditions.
Phytochromes encompass a diverse collection of biliproteins that enable cellular light perception by photoconverting between a red-light (R)-absorbing ground state—Pr and a far-red light (FR)-absorbing active state—Pfr. In Arabidopsis thaliana there are five phytochromes, designated phytochrome A (phyA) to phytochrome E (phyE). Phytochrome B (phyB) is the predominant phytochrome regulating de-etiolation responses in R light and shade avoidance. Phytochromes are synthesized in the cytosol as an inactive Pr form, and are converted to the biologically active Pfr form by light irradiation which then is translocated into the nucleus. Phytochromes play fundamental roles in photoperception by a plant and adaptation of its growth to the ambient light environment.